Flexible optical fiber ribbon with ribbon body flexibility recesses

ABSTRACT

A flexible optical ribbon and associated method is provided. The ribbon includes a plurality of optical transmission elements and a polymeric ribbon body surrounding the plurality of optical transmission elements. The ribbon body includes a plurality of recesses formed in the ribbon body, and each recess has a depth extending from the first major surface toward the plurality of optical transmission elements and a length extending along the ribbon body between a first recess end and a second recess end. The first recess end is defined by a concave curved surface of the polymeric ribbon body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/346,069, filed on Nov. 8, 2016, which claims the benefit of priorityto U.S. Application No. 62/260,715, filed on Nov. 30, 2015, bothapplications being incorporated herein by reference.

BACKGROUND

The disclosure relates generally to optical fibers and more particularlyto optical communication or fiber ribbons. Optical fibers have seenincreased use in a wide variety of electronics and telecommunicationsfields. Optical fiber ribbons may hold multiple optical fibers togetherin a group or array. The optical fiber ribbon includes a body formedfrom a material that holds the optical fibers together and/or thatprovides structure that assists in the handling and connecting of theoptical fibers of the ribbon to various components or devices.

SUMMARY

One embodiment of the disclosure relates to a flexible optical ribbonhaving a plurality of optical transmission elements each having alongitudinal axis, and a polymeric ribbon body coupled to, supportingand surrounding the plurality of optical transmission elements, theribbon body defining a width axis, a length axis and a height axis, theribbon body including a first major surface on one side of the pluralityof optical transmission elements, and a second major surface on theother side of the plurality of optical transmission elements, whereinthe height axis is an axis perpendicular to both the first and secondmajor surfaces of the ribbon body, the length axis extends parallel tothe longitudinal axes of the optical transmission elements, and thewidth axis extends perpendicular to both the height axis and the lengthaxis; and a first plurality of recesses formed in the ribbon body, eachrecess having a depth extending from the first major surface toward theplurality of optical transmission elements and a length extending alongthe ribbon body between a first recess end and a second recess end;wherein the first recess end is defined by a concave curved surface ofthe polymeric ribbon body having at least three radiuses of curvature,one in the plane of the height axis, one in the plane of thelongitudinal axis and one in the plane of the width axis.

An additional embodiment of the disclosure relates to an optical ribbonincluding a plurality of optical transmission elements each having alongitudinal axis; and a multi-layer polymeric ribbon body coupled to,supporting and surrounding the plurality of optical transmissionelements, the polymeric ribbon body having a plurality of inner layersegments formed from a first polymeric material, each inner layersegment is a contiguous polymer structure at least partially surroundingat least two of the optical transmission elements and having an innersurface contacting outer surfaces of the at least two opticaltransmission elements; and a single contiguous outer layer formed from asecond polymeric material and surrounding all of the inner layersegments such that outer surfaces of the inner layer segments contactthe outer layer and the outer layer defines a first major surface on oneside of the plurality of optical transmission elements and a secondmajor surface on the other side optical transmission elements, wherein aportion of the outer layer is located between each adjacent inner layersegment such that all of the inner layer segments are held together bythe outer layer; wherein the first major surface defines a firstprofile, the first profile shaped such that, when viewed in lateralcross-section, a distance between the first and second major surfacesdecreases toward a minimum located between adjacent pairs of inner layersegments, wherein the first profile includes a concave curved surface atthe minimum thickness, the curved surface having a radius of curvaturegreater than 0.05 mm.

An additional embodiment of the disclosure relates to a method offorming a flexible optical ribbon that includes providing an opticalfiber ribbon including a plurality of optical fibers embedded in andsurround by a polymeric ribbon body having an outer surface; andremoving portions of the polymeric ribbon body with a laser such that aplurality of recesses are formed along the outer surface of the ribbonbody, wherein each of the recesses is defined, at least in part, by acurved section of the outer surface of the ribbon body, the curvedsection having a radius of curvature greater than 0.05 mm, the radius ofcurvature reducing stress concentration within the recess.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from the description or recognized by practicing theembodiments as described in the written description and claims hereof,as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understand the natureand character of the claims.

The accompanying drawings are included to provide a furtherunderstanding, and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiment(s), andtogether with the description serve to explain principles and operationof the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a flexible optical fiber ribbonaccording to an exemplary embodiment.

FIG. 2 shows a cross-sectional view of the optical fiber ribbon of FIG.1 taken along the line 2-2 according to an exemplary embodiment.

FIG. 3 shows a detailed view of a portion of the outer surface of theoptical fiber ribbon of FIG. 1 according to an exemplary embodiment.

FIG. 4 shows a system and process for forming a flexible optical fiberribbon according to an exemplary embodiment.

FIG. 5 shows a cross-sectional view of an optical fiber ribbon prior torecess formation according to an exemplary embodiment.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of an opticalribbon are shown. In general, the ribbon embodiments disclosed hereinare configured to provide improved flexibility while also limiting thepotential for unwanted cracking or splitting within the ribbon body ormatrix. In various embodiments, optical transmission elements (e.g.,optical fibers) are coupled to and supported by a ribbon body. Theribbon body is formed from a material, such as a polymer material, andis configured to provide sufficient support, structure and protection tothe optical fibers of the ribbon, while at the same time allowing theribbon to be bent during installation, use, etc. Specifically, theoptical fiber ribbon discussed herein includes a plurality of recessesformed in the ribbon body, and by providing areas of decreased ribbonmatrix thickness the flexibility of the ribbon is improved.

The recesses of the ribbon embodiments discussed herein are formedhaving one or more rounded or radiused surfaces defined by curvedsurface of the ribbon body located at the end of each recess and/oralong the bottom of the recess. In contrast to some flexible fiber opticribbon designs that include rectangular or angularly shaped flexibilitystructures, Applicant has found that a rounded recess shape reducesstress concentration (as compared to angular designs), which in turnimproves ribbon performance by reducing the chance of unwanted ribbonsplitting that may otherwise tend to form at stress concentration siteswithin squared recesses.

In particular embodiments, Applicant has developed a ribbon includingrecesses with curved end sections that are defined by at least threeradiuses of curvature, one in each of the orthogonal planes, andApplicant believes that such design provides superior split resistanceperformance. As generally be understood, flexible ribbon body designstypically involve a trade-off between flexibility and structuralintegrity. Utilizing the designs discussed herein, Applicant believesthat ribbon body design discussed herein allows for a more flexibleribbon at a given level of structural integrity as compared to otherflexible ribbon designs, particularly those that utilize rectangular orangular flexibility features.

In various embodiments, Applicant has also developed a method forforming the rounded recesses discussed herein. In particularembodiments, a laser tool (e.g., an ablation laser) is used to removematerial from the ribbon body to form the recesses having the structuresand shapes discussed herein. Further, Applicant believes that, by usinglaser cutting, the rounded flexibility recesses discuss herein can beformed precisely and with little variability between the shape andposition of discrete recesses. In such laser cutting based processes,the shape of the formed recesses are formed by controlling one or moreaspects of the laser, such as laser power, focal point geometry,intensity profile, etc., to form a recess having the desired roundedshape.

Referring to FIG. 1 and FIG. 2, an optical ribbon, such as optical fiberribbon 10, is shown according to an exemplary embodiment. Ribbon 10includes a ribbon body, shown as ribbon matrix 12, and also includes anarray 14 of a plurality of optical transmission elements, shown asoptical fibers 16. Optical fibers 16 are surrounded by and embedded inthe material of ribbon matrix 12, such that ribbon matrix 12 is coupledto and supports optical fibers 16. In the embodiment shown, array 14 isa parallel array of optical fibers in which the longitudinal axes ofeach optical fiber 16 (the axis of each optical fiber 16 perpendicularto the lateral cross-section shown in FIG. 2) are substantially parallelto each other. In other embodiments, the optical fibers may be arrangedin non-parallel arrays within ribbon body 12 (e.g., two by two arrays,staggered arrays, etc.).

In the embodiment shown, ribbon 10 includes a single linear array 14 ofoptical fibers 16. In some other embodiments, ribbon 10 includesmultiple arrays 14 of optical fibers 16. In some embodiments, ribbon 10includes at least two linear arrays 14. In some other embodiments,ribbon 10 includes at least four linear arrays 14. In still otherembodiments, ribbon 10 includes at least eight linear arrays 14. In yetstill other embodiments, ribbon 10 includes at least 16 linear arrays14. In some embodiments, each linear array 14 of ribbon 10 has at leasttwo optical fibers 16. In some other embodiments, each linear array 14of ribbon 10 has at least four optical fibers 16. In still otherembodiments, each linear array 14 of ribbon 10 has at least 8 opticalfibers 16. In yet still other embodiments, each linear array 14 ofribbon 10 has at least 12 optical fibers 16.

In the embodiment shown, each optical fiber 16 in array 14 is the sameas the other optical fibers 16. As will be generally understood, opticalfibers 16 include an optical core 18, surrounded by a cladding layer 20.In various embodiments, optical fibers 16 also each include a coatinglayer 22. Optical core 18 is formed from a material that transmitslight, and optical core 18 is surrounded by a cladding layer 20 that hasa different refractive index (e.g., a lower refractive index) than theoptical core 18, such that optical fiber 16 acts as a waveguide thatretains a light signal within optical core 18.

Coating layer 22 surrounds both optical core 18 and cladding layer 20.In particular embodiments, coating layer 22 is bonded to the outersurface of cladding layer 20, and the outer surface of coating layer 22defines the outer surface of each optical fiber 16. In general, coatinglayer 26 is a layer of one or more polymer materials (e.g., UV curablepolymer materials) formed from a material that provides protection(e.g., protection from scratches, chips, etc.) to optical fibers 16. Inone embodiment, the diameter of optical fiber 16 is about 250 μm.

As noted above, ribbon body 12 is structured to provide flexibilitywhile limiting stress concentrations that may produce unwanted crackingor separation within ribbon body 12 during use, handling, installation,etc. In the embodiment shown, ribbon matrix 12 includes a plurality ofinner layer segments 26 and an outer layer 28. Each inner layer segment26 is formed from a single continuous layer of polymeric material andincludes an inner surface that is in contact with the outer surfaces ofoptical fibers 16. In this arrangement, optical fibers 16 are embeddedin, and each fiber is at least partially surrounded by, the material ofan inner layer segment 26. In such embodiments, inner layer segments 26are bonded, adhered or coupled to the outer surface of each opticalfiber 16 surrounded by the segment, and specifically are coupled to theouter surface of fiber coating 22.

In the embodiment shown, each inner layer segment 26 surrounds at leasttwo optical fibers 16. In the particular embodiment shown, each innerlayer segment 26 surrounds two optical fibers 16. In other embodiments,inner layer segment 26 may surround 3, 4, 5, 6, etc. optical fibers 16.In another embodiment, ribbon body 12 may include a single inner layer26 that surrounds all of the optical fibers 16 of ribbon 10. In general,inner layer segments 26 facilitate splitting out and connecting pairs orgroups of fibers that are to remain together following splitting ofouter layer 28.

Outer layer 28 is a single contiguous layer of polymeric material thatsurrounds inner layer segments 26. Outer layer 28 includes an innersurface that is in contact with an outer surface of inner layer segments26. Further, outer layer 28 has an outer surface 30 that includes afirst major surface, shown as upper surface 32, and a second majorsurface, shown as lower surface 34.

In some embodiments, outer layer 28 and inner layer 26 may be formedfrom the same type of material. In other embodiments, outer layer 28 isformed from one type of polymer material and inner layer 26 is formedfrom another type of material. In some embodiments, inner layer segments26 may be formed from a low modulus material, and outer layer 28 may beformed from a high modulus material. In other embodiments, inner layersegments 26 may be formed from a high modulus material, and outer layer28 may be formed from a low modulus material. In one embodiment, innerlayer segments and outer layer 28 are formed from UV curable acrylatematerials. In other embodiments, inner layer segments 26 and/or outerlayer 28 may be formed from thermoplastic or thermoset materials.

In various embodiments, inner layer 26 has a lateral cross-sectionalshape configured to reduce stress concentration and unwanted splittingof ribbon body 12. In the embodiment shown, each inner layer 26 includesthickened end sections 36. Each end section 36 has outer surfaces 38 atboth the upper and lower ends of thickened end sections 36. In someembodiments in which portions of outer layer 28 are removed formingflexibility grooves, portions of outer surfaces 38 become exposed withinthe grooves defining a portion of the outermost surface of ribbon 10within the grooves.

Referring to FIG. 1, ribbon 10 includes a plurality of recesses, shownas grooves 40. In general, grooves 40 are formed in a pattern along thelength of ribbon 10, and through the alternating pattern of increasedand decreased ribbon body thickness provided by grooves 40, flexibilityof ribbon 10 is increased (e.g., relative to a ribbon body withoutgrooves 40). As a frame of reference, the position of the variouscomponents and features of ribbon 10 can be described in relation to awidth axis 42, a length axis 44 and a height axis 46. As shown in FIG.1, height axis 46 is perpendicular to upper surface 32 and to lowersurface 34, and generally defines the thickness dimension of ribbon 10.Length axis 44 extends longitudinally and generally parallel to thelongitudinal axes of the optical fibers 16, and width axis 42 extendsgenerally perpendicular to height axis 46, to length axis 44 and to thelongitudinal axes of optical fibers 16.

In general, grooves 40 are depressions formed in ribbon body 12, suchthat grooves 40 extend inward from upper surface 32 toward opticalfibers 16. As shown, grooves 40 are generally defined, at least in part,by a shaped outer surface portion 45 of upper surface 32. As shown inFIG. 2, ribbon 10 includes a second group of grooves 40 located alonglower surface 34. The lower set of grooves 40 extend inward from lowersurface 34. It should be understood that while the description of theflexibility recesses of ribbon 10 are described herein in relationprimarily to grooves 40 located at upper surface 32, grooves 40 locatedon lower surface 34 may include any combination of structures, shapes,dimensions, etc. discussed herein.

As shown in FIG. 1, each groove 40 has a central portion 47 extendingbetween opposing ends 48 and 50. As shown best in FIGS. 2 and 3, each ofthe opposing ends 48 and 50 are defined by a concave curved surface,shown as curved surfaces 52 and 54, formed in ribbon body 12. Concavecurved surfaces 52 and 54 each have at least one radius of curvature R1in at one least one of the height axis plane, the length axis plane orthe width axis plane. In the various embodiments, concave curvedsurfaces 52 and 54 are defined by curvatures in all of the threeorthogonal planes, and in such embodiments, concave curved surfaces 52and 54 each have three radiuses of curvature, one in the height axisplane, the length axis plane and the width axis plane, which define thesurface curvature. In the specific embodiment shown, concave curvedsurfaces 52 and 54 are substantially partial spherical surfaces havingthree equal radiuses of curvature R1, one in the height axis plane, thelength axis plane and the width axis plane, which define the surfacecurvature. In such spherical embodiments, each of the radiuses ofcurvature within each orthogonal plane is within 1% of each other, andmore specifically within 0.1% of each other, resulting in a partialsubstantially spherical surface.

In various embodiments, the shape of the concave curved surfaces 52 and54 are designed to provide both flexibility to ribbon 10 and improvedcrack resistance. It is believed that improved crack resistance isprovided by the curved surfaces discussed herein by reducing stressconcentration that otherwise tends to occur at the corners of morerectangular/angular ribbon body flexibility structures. In variousembodiments, R1 in one or more of the height axis plane, the length axisplane and the width axis plane is greater than 0.05 mm, specifically isbetween 0.05 mm and 0.125 mm, and more specifically is about 0.1 mm(e.g., 0.1 mm plus or minus 1%). In specific embodiments, as shown bestin FIG. 3, R1 in one or more of the height axis plane, the length axisplane and the width axis plane is substantially equal to (e.g., withinplus or minus 1%) half of groove width, W1. In such embodiments, W1 isbetween 0.1 mm and 0.3 mm, and specifically is about 0.25 mm (e.g., 0.1mm plus or minus 1%). In various embodiments, concave surfaces 52 and 54have the same radiuses of curvature as each other, such that each groove40 is symmetrical about its midpoint in the length direction and is alsosymmetrical about its midpoint in the width direction.

In particular embodiments, it is believed that the combination of curvedsurfaces forming grooves 40 and the enlarged end portions 36 of innerlayer segments 26 provide a structure that improves crack resistance.Further, the double layered structure of ribbon body 12 discussed hereinmay allow for the removal of additional material of ribbon body 12forming larger grooves as compared to a similar groove structure formedin a single layered ribbon body, which in turn increases ribbonflexibility.

Referring to FIG. 2, upper and lower surfaces 32 and 34 of ribbon body12, including those portions forming grooves 40, define a profile thatextends the width of ribbon 10, when viewed in lateral cross-section. Insuch embodiments, the profile defined by ribbon body 12 is shaped suchthat ribbon body 12 has a maximum thickness, T1, at a location towardthe center of each inner layer segment 26, at a position generally aboveoptical fibers 16. The profiles on both upper and lower surfaces 32 and34 slope inward toward a minimum thickness, T2, located at a positionbetween adjacent pairs of inner layer segments 26. In the embodimentshown, portions 51 of outer layer 28 is located between each adjacentpair of inner layer segments 26 and acts to hold together ribbon 10 byproviding a common structure connected to each adjacent inner layersegments 26.

In various embodiments, T2 is selected to be thin enough that ribbon 10is flexible and allows the ribbon segments to be separated by a user,for example tearing or cutting when desired, while at the same timebeing thick enough that ribbon matrix 12 is resistant to unwantedtearing. The minimum thickness is located at a position along the heightaxis between the upper most and lower most surfaces of adjacent opticalfibers 16. In this arrangement, the minimum thickness is at a positionrecessed below both the upper and lower outer surfaces of optical fibers16 and is generally centered at the middle plane of the ribbon 10. Invarious embodiments, T2 is less than the outer diameter of opticalfibers 16 and more specifically is less than 50% of the outer diameterof optical fibers.

As shown best in FIG. 2, each groove 40 includes a curved bottom surface52 that is located at the point of the minimum thickness T2. Curvedbottom surface 52 is the portion of the profile that defines thetransition from the minimum thickness to the groove sidewalls thatextend upward toward the maximum thicknesses T1. Curved bottom surface52 is also defined by a radius of curvature R2, and in the particularembodiment shown, the value of R2 is same as the radius of curvaturethat defines the groove ends R1, as discussed above. In otherembodiments, curved bottom surfaces 52 may have a different radius ofcurvature that may be either greater than or less than R1.

Referring to FIG. 1 and FIG. 3, grooves 40 are arranged in pattern alongouter surfaces 32 and 34. In one embodiment, the pattern of grooves 40on upper surface 32 is the same as the pattern of grooves on lowersurface 34, and in a specific embodiment, the patterns on both uppersurface 32 and lower surface 34 are positioned at the same location aseach other such that the profile of the outer surface of ribbon body 12is symmetrical about the middle plane of ribbon 10 (e.g., a plane in thewidth axis intersecting the center points of optical fibers 16).

As shown in FIG. 1, grooves 40 are discrete grooves arranged such thatareas of unrecessed (e.g., substantially planar) portions 56 of outersurfaces 32 and 34 are located between adjacent grooves 40. Grooves 40are arranged in longitudinally aligned columns in which a section ofunrecessed outer surface portions 56 spaces each groove 40 from thelongitudinally adjacent groove. As shown in FIG. 3, unrecessed outersurface portions 56 have a length L1 in the longitudinal direction, andin various embodiments, L1 is between 1 mm and 15 mm, specificallybetween 3 mm and 7 mm, and more specifically is about 5 mm (e.g., 5 mmplus or minus 1%). It is believed that the L1 spacing provided by theribbon body discussed herein is relatively low (resulting in increasedgroove density) which in turn increases ribbon flexibility. It isfurther believed that because of the relatively large radiuses ofcurvature, R1, defining the shape of grooves 40, and the resultingreduction in stress concentrations, L1 is lower than in at least someother ribbon designs that utilize a more rectangular/angled profile toform flexibility enhancing structures.

As shown in FIG. 1, grooves 40 are also spaced from each other in thedirection of width axis 42 such that grooves 40 form rows across thewidth of ribbon 10. In this arrangement, a section of unrecessed outersurface portions 56 spaces each groove 40 from the widthwise adjacentgroove 40. As shown in FIG. 1, unrecessed outer surface portions 56 havea width W2 in the width direction, and in various embodiments.

In various embodiments, as shown in FIG. 1 and FIG. 2, each longitudinalcolumn of grooves 40 is located at an aligned position between adjacentinner layer segments 26. This arrangement results in the positioning ofthe areas of minimum thickness, T2, discussed above, which in turnprovides points of flexibility between the adjacent inner layer segments26. Further, adjacent columns of grooves 40 are staggered relative toeach other as shown by the dimension L2.

Referring to FIG. 4 and FIG. 5, a method of forming a flexible opticalribbon, such as ribbon 10, is shown according to an exemplaryembodiment. As shown in FIG. 4, optical fiber ribbon 10 is provided to alaser cutting station, shown as laser 60. As shown in FIG. 5, the ribbon10 provided to laser 60 has a ribbon body having substantially flatupper and lower surfaces 32 and 34. As shown in FIG. 5, prior toformation of grooves 40, ribbon body 12 includes regions 62 of outerlayer 28 that will be removed to form grooves 40.

As shown in FIG. 4, laser 60 generates and directs laser beams 64 ontoouter surfaces 32 and 34 of ribbon 10 in the desired pattern to formgrooves 40, as discussed above. In various embodiments, laser beams 64remove, cut or ablate a portion of ribbon body 12 to form grooves 40. Invarious embodiments, laser beams 64 are shaped and/or focused to formthe curved surfaces 52 and 54 discussed above, and in a specificembodiment, laser beams 64 are shaped and/or focused to formsubstantially spherical curved surfaces 52 and 54. In some embodiments,laser beams 64 have an intensity profile that is related to and isadjusted to create the desired shape of curved surfaces 52 and 54. In atleast some embodiments, it is believed that inner layer segments 26provide a layer of protection to optical fibers 16 during laser cutting,which allows for the use of laser 60 to form grooves having a relativelylarge depth D1, without laser 60 causing damage to optical fibers 16.

It is believed that in contrast to blade-type cutting systems, laser 60allows for the accurate, fast and consistent formation of the curvedsurfaces defining grooves 40 as discussed above. Further, it is believedthat grooves 40 would be difficult or impossible to form by depositingthe ribbon matrix precursor material in the desired pattern followed bycuring due to the imprecision of deposition devices that need to startand stop the flow of ribbon material during deposition. In otherembodiments, grooves 40 may be formed through other non-contact removalmethods such as sand blasting. In other embodiments, grooves 40 may beformed using a blade or grinding tool to remove the material ribbon body12 to form the desired shape of grooves 40.

In various embodiments, the ribbon bodies discussed herein may be formedby applying a polymer material, such as a UV curable polymer material,around optical fibers 16 in the desired arrangement to form a particularribbon body. The polymer material is then cured forming the integral,contiguous ribbon body while also coupling the ribbon body to theoptical fibers. In other embodiments, the ribbon bodies discussed hereinmay be formed from any suitable polymer material, includingthermoplastic materials and thermoset materials.

It should be understood that the optical ribbons discussed herein caninclude various numbers of optical fibers 16. In various exemplaryembodiments, the optical ribbons discussed herein may include 2, 4, 6,8, 10, 12, 14, 16, 24, etc. optical fibers or transmission elements(e.g., optical fibers 16). While the ribbon embodiments discussed hereinare shown having optical fibers 16 arranged in a substantially parallel,linear array, optical fibers 16 may be arranged in a square array,rectangular array, a staggered array, or any other spatial pattern thatmay be desirable for a particular application. In various embodiments,optical fibers 16 can include a wide variety of optical fibers includingmulti-mode fibers, single mode fibers, bend insensitive/resistantfibers, etc. In other embodiment, the optical ribbons discussed hereinmay include a multi-core optical fiber located within ribbon matrix 12.In this embodiment, a single, integral optical structure having multipleoptical transmission elements (e.g., multiple optical cores surroundedby cladding) may be provided, and the single multi-core optical fiber isembedded in one of the stress-isolating ribbon matrix embodiments and/orcoated with a coating layer (e.g., inner segment layers 26) as discussedherein. In specific exemplary embodiments, optical fibers 16 may beCorning's Ultra® SMF-28, ClearCurve® LBL and ZBL G.652 compatibleoptical fibers.

The optical fibers discussed herein may be flexible, transparent opticalfibers made of glass or plastic. The fibers may function as a waveguideto transmit light between the two ends of the optical fiber. Opticalfibers may include a transparent core surrounded by a transparentcladding material with a lower index of refraction. Light may be kept inthe core by total internal reflection. Glass optical fibers may comprisesilica, but some other materials such as fluorozirconate,fluoroaluminate, and chalcogenide glasses, as well as crystallinematerials, such as sapphire, may be used. The light may be guided downthe core of the optical fibers by an optical cladding with a lowerrefractive index that traps light in the core through total internalreflection. The cladding may be coated by a buffer and/or anothercoating(s) that protects it from moisture and/or physical damage. Thesecoatings may be UV-cured urethane acrylate composite materials appliedto the outside of the optical fiber during the drawing process. Thecoatings may protect the strands of glass fiber.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the disclosed embodiments. Since modificationscombinations, sub-combinations and variations of the disclosedembodiments incorporating the spirit and substance of the embodimentsmay occur to persons skilled in the art, the disclosed embodimentsshould be construed to include everything within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An optical ribbon comprising: a plurality ofoptical transmission elements each having a longitudinal axis; and amulti-layer polymeric ribbon body coupled to, supporting and surroundingthe plurality of optical transmission elements, the polymeric ribbonbody comprising: a plurality of inner layer segments formed from a firstpolymeric material, each inner layer segment is a contiguous polymerstructure at least partially surrounding at least two of the opticaltransmission elements and having an inner surface contacting outersurfaces of the at least two optical transmission elements; and a singlecontiguous outer layer formed from a second polymeric material andsurrounding all of the inner layer segments such that outer surfaces ofthe inner layer segments contact the outer layer and the outer layerdefines a first major surface on one side of the plurality of opticaltransmission elements and a second major surface on the other sideoptical transmission elements, wherein a portion of the outer layer islocated between each adjacent inner layer segment such that all of theinner layer segments are held together by the outer layer; wherein thefirst major surface defines a first profile, the first profile shapedsuch that, when viewed in lateral cross-section, a distance between thefirst and second major surfaces decreases toward a minimum locatedbetween adjacent pairs of inner layer segments, wherein the firstprofile includes a concave curved surface at the minimum thickness, thecurved surface having a radius of curvature greater than 0.05 mm.
 2. Theoptical ribbon of claim 1, wherein each of the optical transmissionelements has an outer diameter, wherein the minimum thickness is lessthan the outer diameter of the optical transmission elements.
 3. Theoptical ribbon of claim 2, wherein each of the optical transmissionelements has an outer diameter, wherein the minimum thickness is lessthan 50% of the outer diameter of the optical transmission elements. 4.The optical ribbon of claim 1, wherein the second major surface definesa second profile, the second profile shaped such that, when viewed inlateral cross-section, the second profile includes a concave curvedsurface at the minimum thickness, the curved surface of the secondprofile includes a radius of curvature greater than 0.05 mm.
 5. Theoptical ribbon of claim 4, wherein the radius of curvature of the curvedsurface of the first profile and the radius of curvature of the curvedsurface of the second profile are less than 0.125 mm.